The Epidemiology and Biostatistics Core will support the management of all the study cohorts, community participation, data quality, statistical analysis and specimen handling. The Core will support all four CAPRISA projects and will support the management of all field procedures, including the methods and procedures used to identify, recruit, enroll and follow up subjects. Several cohorts are involved in the CAPRISA studies. The HIV evolving epidemiology study will be conducted in a rural community of KwaMncane in KwaZulu-Natal. The acute seroconvertor study will include high risk sex workers at truck stops, while the highly exposed persistently seronegative individuals study will draw on subjects from a truck-stop sex worker cohort in KwaZulu-Natal and from HIV-negative men who are repeat sexually transmitted disease clinic attendees over at least 4 years. Newly diagnosed tuberculosis patients who are co-infected with HIV will be recruited for the antiretroviral therapy trial from the Communicable Disease Center in Durban and the Ernest Oppenheimer mine hospital in Welkom. Methods of cohort establishment, including recruitment and retention are well developed. Strategies for community participation at the study sites will include the establishment of a Community Advisory Board. Community education programs will be developed in collaboration with community representatives. Data management and biostatistical support will be provided by this Core to all the projects. A research database, with controlled access, will be available to CAPRISA investigators. It will serve as a central repository for the demographic, laboratory, epidemiological and clinical data. This Core will be responsible for internal and external data quality control and support will be provided for the study designs, sample size and power estimation, statistical analysis of data, and reporting of results. This core will use the data to develop models of disease transmission which should further our understanding of the dynamics of the HIV epidemic. The specimen repository will be managed by this Core. Appropriate collection, processing and storage of specimens will ensure that high quality blood and mucosal samples are available for future studies. A computerized sample inventory and retrieval system using the Laboratory Data Management System will be set up.